Conventionally, methods for adjusting control parameters have been known for use in control apparatuses of electric motors. Such methods include the technology disclosed in Patent Literature 1, for example. The control apparatus disclosed in Patent Literature 1 calculates optimal control parameters on the basis of gain characteristics and phase characteristics, by using frequency characteristics of a drive system.
FIG. 9 is a view of a configuration of a control apparatus of a conventional electric motor. Control apparatus 151 shown in FIG. 9 is one example of conventional technologies. Usually, when electric motor 101 is driven, control apparatus 151 of the motor shown in FIG. 9 operates such that switch 109 is connected to an a-side terminal. At this moment, parts involved in the apparatus perform the following operations.
That is, mechanical system 104 includes motor 101, load 102, and motor position detector 103. Load 102 is driven by motor 101. Detection position θm of motor 101 is output from motor position detector 103. Speed computing unit 106 computes detection speed vm of the motor, from the amount of variation per unit time in detection position θm. Speed computing unit 106 outputs thus-computed detection speed vm of the motor. Position controller 107 outputs speed command vr such that detection position θm follows position command θr. Position command θr is inputted from the outside of control apparatus 151 of the motor. Speed controller 108 outputs torque command τr such that detection speed vm of the motor follows speed command vr. Thus-output torque command τr turns to new torque command τr2, via filter 110. New torque command τr2 is inputted to torque controller 111. Motor 101 is controlled by the output from torque controller 111.
When the control parameters are adjusted, control apparatus 151 of the motor shown in FIG. 9 operates such that switch 109 is connected to a b-side terminal. At this moment, parts involved in the apparatus perform the following operations.
That is, torque command generator 112 for measuring frequency characteristics outputs first torque command τr1. First torque command τr1 contains a plurality of frequency components, such as a maximum length sequence (M-sequence) signal, for example. The M-sequence signal is a random binary bit-string signal indicated as either 0/1 or −1/1. Motor 101 is driven in accordance with first torque command τr1. At this moment, first torque command τr1 and detection speed vm of the motor are inputted to control parameter adjuster 115.
Control parameter adjuster 115 computes frequency characteristics from first torque command τr1 to motor speed vm. Control parameter adjuster 115 computes a control parameter of speed controller 108, a control parameter of position controller 107, and a control parameter of filter 110, by using the computed frequency characteristics, such that the operations of the control system of the motor is stabilized and the responsivity of the control system of the motor is enhanced. The control system of the motor includes speed controller 108, position controller 107, and filter 110.